I really need help. Please.

[Derek09]

Hi, and sorry for all the post but i wasn't having a lot of exposure or replies.
To begin with,
I have a Corsair K70 Rgb Rapidfire Mk1 keyboard.
Recently the A key decided not to work anymore, so I decided to replace it with the right Win R key.
But when I unsoldered the A key I made a mistake, and so I melted the little ring that acts as a contact...

But Win R no problem everything went well.

I soldered the key A to the resistor because it was not sticking on the initial place because of my mistake.
But nothing worked...

So I analyzed and I saw that the keyboard works in series by line.

So I soldered the key on another key on the same line, but when I click on the key it does anything (aeftfjf) for example...

I know that the work is not very beautiful unfortunately, but I can not do more beautiful with the equipment I have.

Do you have a solution? I would really appreciate it!
Thank you!

[Win R key](https://ibb.co/8XKgWY1)
[A key soledered to the other key](https://ibb.co/9qMpgG1)





Here is my second attempt and the pcb

[yui]

keyboards uses a matrix for their switches. one leg is usually connected in rows while the other is in columns,although the matrix can be rather different on gaming boards especially near wasd and qwer. annoyingly the traces that would help us are on the top of the pcb under the switches, so can't trace that way, now you will need to makes guesses maybe instead of soldering to the next in line try to the one above?
oh and those are diodes, not resistors, just so that you know what to search better if you need it.
one way you could solve that is if you have a multi-meter and know someone with the same board as you, you could try beep your way to the closest connected switch and be sure to do the right fix on 1st try.
oh and maybe someone more knowledgeable than me will see this thread a bit later and come to help you better. i am far from the best on this forum.

[Maledicted]

oh and maybe someone more knowledgeable than me will see this thread a bit later and come to help you better. i am far from the best on this forum.

Paging suicidal_orange

Everything but the a key works otherwise without your jumpers, or did lifting the pad kill chunks of that row? I'm lazy, so I always just solder a long jumper from the good pad on a switch that doesn't work, plug the keyboard in, and just touch it to the opposite pad of nearby switches until I find the closest one that registers the key I need. Then I desolder the test jumper and solder a more permanent jumper from the leg with the bad pad to the same leg of the switch that ended up being an ideal surrogate.

[Derek09]

Thank you to all! I will try.
But is there someone who know what is the name of some of the pro here? Would be really appreciated.
Thank you.

[Derek09]

Here is the problem without anything solder Apart from the resistor.

[Maledicted]

Thank you to all! I will try.
But is there someone who know what is the name of some of the pro here? Would be really appreciated.
Thank you.

suicidal_orange's profile was already linked in my previous comment.

Wait, so both pads for A are toast? Could you see a trace under the solder mask running from the lower leg to the diode you soldered it to, or could it have run somewhere else? If that leg is soldered right, and only the a key isn't working (you haven't said whether or not this is the case), you should just have to try what I suggested before.







Does this make sense?

[suicidal_orange]

Tried to look but the thumbnails don't want to load let alone the full size pics so I can't see anything.  It's been one of those months!

As I read it when you press the A key it types AEFTJ?  I'll try and work out the matrix tomorrow.   A F and J have two keys between so that could be a start...

[Maledicted]

As I read it when you press the A key it types AEFTJ?  I'll try and work out the matrix tomorrow.   A F and J have two keys between so that could be a start...

I figured it was because he previously soldered random nearby switches in series. ¯\_(ツ)_/¯

[suicidal_orange]

And I can see!

So the diodes are linked in physical columns and although randomly positioned all seem to be connected to the lower switch pin, so the fix from A to the diode looks good - don't remove it.  If it were a DIY board your fix to S and Caps would have worked too but professionals don't like to make it that easy.

Other than that Maledicted's pictures are right - you want to touch between all the surrounding pins to your fix until you type an A then solder the jumper to the other pin on A.  If you got AEFTJ all at once E would be my bet for the closest option.

I figured it was because he previously soldered random nearby switches in series. ¯\_(ツ)_/¯

Could be, but if you bypass a diode you can output all the keys connected to a "row" or "column" (terms that don't make much sense on most commercial boards...) which can be useful in working out what's connected to what

[Derek09]

Thank you for all your answers, and also sorry for my very late reply, but I have tried everything that has been said and nothing works and I don't really understand why...
I've given up a bit and I don't know if there is anything to do? And that's why I had given up on it. But now I'm just thinking about the keyboard again haha.

And also the keyboard seems to have some kind of dab (Ribbon Cable) that connects when the whole thing is closed and clipped, could this be causing the problem?

Because there was a time when everything was working fine and when I closed the keyboard the problem came back and it stayed there, even when the keyboard was opened again. 

[Derek09]

Also i've tried with a jumper and it didn't work

[suicidal_orange]

No problem - it's you that's had a broken board for months

The ribbon cable could be under a switch pin which has punctured it causing a short - this could explain all the keys activating at once, though you said that only happened after you started soldering so doesn't sound likely.  No harm checking it for physical damage but if it looks good it is (I would expect it to break lots of keys if it is damaged)

Lets start at the beginning - remove the jumper wire going to Caps (I've coloured over it in green) because if the designer is going to do anything random it won't be in the letters.  What does the A key type now, if anything?



If you already removed both jumpers or A types nothing even with the jumper touch a wire between orange and each of the reds and one of them should type an A.  If it does solder a jumper between that red and blue.  If any red typed something different please say which typed what - "nothing works" doesn't help us understand.

[Derek09]

Thanks, I'll try that and get back to you afterwards!